Most of light, which is reaching the surface of the earth from the sun, is absorbed by the atmosphere, and a part of the light arrives at the surface of the earth. In the light, a wavelength region of approximately 700 nm to 1 mm of which the wavelengths are longer than wavelengths of a red wavelength region in a visible ray region is called infrared ray. In the infrared ray, especially, a wavelength region of 4000 nm to 1 mm is called far-infrared ray. Far-infrared rays are also called heat rays which are generated in a heating equipment to be used in daily life.
Meanwhile, if a temperature rise caused by absorbing far-infrared rays can be suppressed, it may be possible to use it in various industry fields. For example, among solar cell modules used in a solar power generation panel, it is known that, when a temperature of a solar cell module using crystalline silicon increases, the output voltage decreases. This is because, when a forbidden band width decreases at a high temperature, the output voltage decreases. Accordingly, when the infrared ray can be selectively reflected on a surface of the solar cell module, it is possible to suppress a temperature rise within the module so that a decrease in output voltage may be avoided.
If a pigment that reflects infrared ray is mixed with a paint composition, it is possible to give an effect of reflecting at least the infrared ray to a coaing film. As the conventionally known pigments that reflect the infrared ray, for example, there are metal oxide-based pigments such as a titanium oxide, a chrome oxide, a cobalt oxide and a barium oxide. However, in the case an infrared ray reflective paint is compounded using such pigments, brightness of a color tone is greatly limited. For this reason, Japanese Patent Application Laid-Open No. 11-302549 (Patent Document 1) discloses a composition having an excellent function of reflecting the infrared ray regardless of the brightness of the color tone.